This document discusses breast cancer risk factors and prevention. It states that most women who develop breast cancer have no known risk factors besides age. Some factors that can increase risk include family history of breast cancer, certain genetic mutations, dense breast tissue, early menarche or late menopause, not having children or having them later in life, hormone therapy, radiation exposure, alcohol consumption, obesity, and not breastfeeding. Maintaining a healthy lifestyle through diet, exercise, and limiting alcohol can help lower risk, though does not guarantee prevention.

1. Breast Cancer Risk Factors and Prevention
"What's my risk of breast cancer?" is a question many women ask their doctors. Doctors have
tools to help estimate a woman's personal risk. Most women who get breast cancer have no
known risk factors besides age. Many women with one or more risk factors never get breast
cancer. So it's impossible to know who will actually get breast cancer.
Factors that affect a woman's risk of breast cancer include:
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Age. The strongest risk factor is age. Risk goes up as a woman gets older. Most women who get
breast cancer are older than 50.
Personal history of breast cancer. Women who have had breast cancer in one breast are more
likely to get it in the other breast.
Family history. Having a mother, sister, or daughter who has had breast cancer increases a
woman's risk. The risk is higher if her family member got breast cancer before age 40. A
woman’s risk also is increased if more than one family member on either her mother’s or
father’s side of the family has had breast cancer.
Inheriting certain harmful gene mutations. Here are some key points about genes and breast
cancer:
o Inheriting changes to certain genes, such as BRCA1 and BRCA2, greatly increases the risk
of breast cancer.
o Inherited genetic changes account for about 10 percent of all breast cancers.
o If you have a relative who has a harmful gene mutation, you may want to talk to a
genetic counselor to learn more about your personal risk. You may also want to seek
genetic counseling if your family history of cancer suggests a gene mutation.
o A woman known to carry a harmful gene mutation should talk to her doctor about ways
to try to lower her breast cancer risk or find breast cancer early.
Certain breast changes that are not cancer. Women who have certain types of abnormal breast
changes, such as atypical hyperplasia, ductal carcinoma in situ, and lobular carcinoma in situ,
have a higher risk. These changes are found during a breast biopsy.
Breast tissue that is dense on mammogram. Women whose breasts have more dense tissue
relative to fatty tissue have a higher risk than women of about the same age who have little or
no dense breast tissue.
Menstrual and reproductive history. Getting your first menstrual period before age 12
increases breast cancer risk. Reaching menopause after age 55 increases breast cancer risk.
Never having children or having children after age 30 also increases risk. Women who have a
first baby before age 20 have a lower risk.
Taking the hormones estrogen and progestin. Using menopausal hormone therapy containing
both estrogen and progestin for more than five years increases breast cancer risk. It's not clear
whether estrogen-only therapy affects risk. Using birth control pills may slightly increase the risk
of breast cancer in current users, but this risk returns to normal over time.
Radiation therapy to the chest. Radiation therapy to the chest for the treatment of cancer
increases breast cancer risk. Risk depends on the dose of radiation and age of treatment. The
risk is highest for radiation treatment used during puberty.
Body weight. The chance of getting breast cancer after menopause is higher in women who are
overweight or obese.

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Drinking alcohol. The more alcohol a woman drinks, the greater her risk of breast cancer.
Taking DES. The drug DES, or diethylstilbestrol (dye-ETH-uhl-stil-BES-trol), was given to some
pregnant women in the United States between about 1940 and 1971 to prevent miscarriage. (It
is no longer given to pregnant women.) Women who took DES during pregnancy may have a
slightly increased risk of breast cancer.
Physical activity. Women who are not physically active throughout life may have an increased
risk of breast cancer. Strenuous exercise for more than four hours per week may help lower
breast cancer risk. Also, being active can help women prevent overweight and obesity, which
are known risk factors for breast cancer in women who have reached menopause.
Breastfeeding. Women who breastfeed have a lower risk of breast cancer.
Race. In the United States, white women have the highest breast cancer rates. Yet women of all
races get breast cancer. African-American women are more likely to die from breast cancer than
white women. One reason is that cancer is often found in African-American women at a later,
more advanced stage, when it may be harder to treat.
Researchers continue to look for other factors that might affect a woman's risk of getting breast
cancer. Factors that do not appear to affect a woman's breast cancer risk include:
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Breast implants
Miscarriage or abortion
Underarm deodorant and antiperspirants
Smoking – Although neither smoking nor secondhand smoke has been shown to increase the
risk of breast cancer, they do have other cancer-causing effects. Smoking is the number one risk
factor for lung cancer.
If you're looking for ways to lower your breast cancer risk, focus your efforts on a healthy
lifestyle. Wholesome and well-balanced meals and regular physical activity can help you to
maintain a healthy weight. Limit alcohol to no more than one drink a day. Whether these steps
will protect you from breast cancer is not certain. But living a healthy lifestyle is a cornerstone of
disease prevention.